45 ACP and 45 Auto are he same round - but not t be confused with a 45 GAP which is a shorter round.    Here is an article on auto vs GAP HERE. I believe since ACP stands for "Automatic Colt Pistol" some manufactures shorten to Auto as to not support Colt.

On a side note - I just noticed you are in Denton county so we are practically neighbors, BTW there is a Gun show in Denton on the 17th and 18th this month.

Thanks for the help and the comp on the 45 GAP.  I will miss the Denton show as it is opening weekend for rifle in Georgia and I still have a lease there for this season.   Have been looking in Texas but not doing a very good job.

Roy L. Bryant

I own a Taurus PT1911 .45acp pistol. It fires flawlessly when I use .45acp ammo, but if I use just .45 auto ammo, it jams all the time. So there has to be a difference between these two types of rounds. Anyone out there knows what the difference might be?

i have a 1911 45 acp/auto kimber target eclips 2.  the rounds are the same  but  u may be useing a brand or bulet type that ur gun does not like there for makeing it jam like .. my mossberg  atr 270 cal shoots better with hornady 130 gr sp then remingtons 130gr corloks it all depinds on the gun.